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When I am firing my electric kiln, I start with the lid propped open about 2 inches and the top peephole out. Then at around 1000 degrees F I shut the lid. The top peephole is open the whole time. I understand that the lid needs to be propped to allow moisture and gasses to escape in the early stages of firing. My questions are:

1) is 1000F an appropriate temp to close the lid?

2) Is it necessary to prop the lid on a ^6 glaze firing as well as the bisque, or only during the bisque (^06)

 

I have been firing this way for a couple years and the pots always come out well. However the lid has badly cracked on both the inside and outside, necessitating repair with kiln cement. I have a large electric Skutt Kiln (I think it's the 1227). Even with my repair, it is all fractured and occasionally falls onto the pots below. The metal handle is also badly rusted and corroded, an issue I didn't notice when I bought this kiln used a couple years ago. 

 

I notice when I close the lid on an 1000F kiln it makes a soft settling crackling noise. I am curious if the cracking lid is from thermal shock when it goes from hot room temp to 1000F. Because of this, i wonder if it's better not to close it so late (and hot) in the firing. Perhaps it's just time for an envirovent. 

 

Is it normal for a lid to start to deteriorate like this? The newer versions of my kiln are made with the hydraulic lid lifter, which I assume lifts it more evenly, without the torque from supporting it on just one part. Please let me know if anyone else has had this cracking lid issue.

-Dana

 

 

 

 

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Post some pics.

 

It's not necessary to prop the lid. Just leave the top peep hole open and you'll be fine. Propping the lid is bad for the lid, and bad for the top rim of the kiln body, and totally unnecessary on kilns with decent switches. The only time propping is necessary is on really old kilns that just have on-off switches (light switches), where propping the lid slows down the firing so things don't blow up. But with low-med-hi or infinite switches it's easy enough to do a slow start, and the top peep will vent out the moisture and fumes just fine.

 

You should be using a vent if the kiln is anywhere near a living space.

 

When you say cracking, do you mean the surface of the lid is cracking and flaking off, or the bricks are cracking apart? Surface cracking and flaking happens on old kilns. The best you can do is scrape off any loose stuff and go over it with some thinned out kiln cement. But even then it'll just keep happening. You ca put a kiln shelf at the top of your load to protect the pots. At some point the lid needs to be replaced, or flipped over if the other side is in better condition, or swapped out with the floor if it's better.

 

The modern hinges are nice, and much easier to lift the lid on a kiln that size. They're not hydraulic, but spring loaded. Retrofitting is kind of a pain and expensive. A cheaper, simpler solution is to rig up a pulley with a counterweight above the kiln.

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Yeah, Neil been meaning to rig up a pulley system for my L & L for years. I have an old econo with the four sections for when I fire larger. Problem was always moving the section with the lid and hinge, and finding the right storage and such to take care of the leftover, but then that meant always moving two sections to put the lidded section on. Long of the short, last time I ordered a lid(extra thick), I put on the old lids handle on opposite side. Easily lift the lid and store on side next to kiln, also easy to put on that fourth section. However, a pulley system would be really nice the older I get.   :huh:

 

 

best,

Pres

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neil has given you very good advice.  so do what he says.  

 

you may have been causing  the breakage by propping the lid so high.  i have propped my lid since 1972 but only half an inch or less using a tiny bit of broken brick or a 1/2 inch post on the metal edge that is folded under the lid and over the top of the wall.  never on just the bricks.  2 inches is a huge amount of stress for that lid to withstand.   

 

my firing pattern is very different from the average potter, i tightly pack and single fire from greenware to glaze.

 

(it is not the temperature that determines when to remove the prop and close the lid, but the moisture coming out of the opening that tells me when.  once i cannot see vapor on a mirror held at the edge of the lid, i can safely close it.  check previous posts for accurate temperature when this is expected.)   

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Thank you all for your responses! I only wish I had joined here earlier and known all along that I didn't need to be propping because it was a lot of trouble. ( I usually fire overnight, so I'd have to wake up to close it). I like the idea of switching my broken lid with my floor piece.

 

what is the best way to attach a new handle to the kiln brick with the metal band? 

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I reused the screws that were holding the handle on the lid when I switched them.  If they are too rusty to use go to a hardware store and buy some replacements, don't forget to take the old one with you for comparison.   Denice

If You replace rusty screws, do so with stainless steel. They're a little more expensive, but they're stronger and won't rust.

JK

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i am thinking about the damaged top.  if it is in bad condition, it seems counterproductive to put all the weight of the loaded kiln on it.

 

If it's just flaking it won't be a problem at all. Better at the bottom than at the top. If the lid is actually cracked, then you can still use it one the floor, but it would be wise to put a piece of sheet metal under it to give it more support. The shelf posts will rest right about where the kiln stand supports the floor, so as long as the outer band is tight the sheet metal will provide enough support for it. It's not ideal, but I've seen cracked floors go for years like that.

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  • 2 years later...

Neil said to use a vent if the kiln is anywhere near a living space. By this I'm assuming that a kiln located in an attached garage is should be vented. Firing newbie here, on second firing (glaze, cone 5 clay) with used Skutt 1018, manual.  Would have to admit to  feeling a little weird (fumes) with the garage door cracked a foot high plus the garage side door wide open. Do you think a vent is still needed, even with both doors wide open? 

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Hi Blue,

Good question!

I'd go with garage door all the way open, and then stay out of the garage whilst firing and limit exposure when peering at the pyrometer readout, cone packs, twiddling switches, etc. - hold breath whenever the kiln is breathing on you, wear glasses when anywhere near, but switch to kiln glasses before looking in at your glowing cones.

If there's a door to the house from the garage, go around.

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  • 1 year later...

I am a new kiln owner and am trying to figure out how to safely shut the kiln lid after keeping it open an inch for ventilation until 800 degrees F. Should I wear 800 degree F resistant gloves? I would be removing the brick keeping the lid up and touching the handle for the lid to put it down. Thank you!

 
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As was mentioned earlier in the thread, you don’t really need to leave your kiln open at all unless its realy old; just the top peep. 

But if you have your heart set, probably some welding gloves are your best bet. If you’re just replacing the top peep at the same point, just a pair of leather garden gloves and some quick work will do.

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19 hours ago, Babs said:

Why are you propping?

I too want to ask this.  In the UK, every electric kiln I have used will not work if the lid or door is not fully shut.  One,  in a school, had a weird key like object that had to be removed from the door lock, and inserted into the controller before the controller would work.  And it could only be removed from the door if that was shut.  It was a bit of a safety overhead, as a number of times, I would be just about to switch it on and would see a pot that had not got in.  

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On 3/22/2021 at 10:40 PM, neilestrick said:

Electrical codes in the UK pay more attention to the safety of the user, in addition to fire safety.

I worked in a grocery store, and we had a cardboard box baler.  I know nowadays, anyone under 18 can't even put boxes in them, let alone run them.  But back when I worked, we were allowed to.  That thing had so many safety features, that I have no idea how a person could harm themselves, without bypassing all said features.  If the gate wasn't down all the way, it wouldn't run.  The grating was pretty tiny so even fingers couldn't get through, so on and so forth.

That said, I did nearly break my arm, when trying to unload the bale.  The mechanism that kicked the bale out, didn't do so fully.  So I climbed over it, and leg pressed it out, not taking into account, that if I was successful, there would no longer be anything between me and the thick steel of the baler's interior...

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Duh. .. I remember in the day when I used a Walker pug mill where the prof had removed the kick bar, and the top grid cover. . .  and the tamper to push the clay into the machine.  Not good when someone slipped on the wet floor as it always was around the pug mill.

 

Some people will dismantle anything safety device for their own convenience.

 

best,

Pres

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When I worked for A.R.T clay, the two mixers were big open top trough style with large rotating mixing blades. They held about a ton of clay each. Anyone could stick their arms in them if they wanted to. We also had an industrial pugmill that didn't feed properly so you had to push the clay in with a stick. Luckily one of the mixers broke down, and the old pugger was on its last legs, so I was able to replace them with better machines, and as part of the deal I installed pressure mats in front of the mixers so they shut down when someone stepped on them.

There was a guy before me that lost a finger on the machine that cut the pugs into 25 pound blocks. It's a wire that goes up and down through the pug, powered by an air cylinder.

Industrial machines are dangerous, but can be made pretty safe as long as people don't disarm the safety systems. I worked for a glass shop that did store fronts, and the chop saw we used for cutting the aluminum frame extrusions had an 20" blade that spun way faster than a typical wood saw. It had hydraulic clamps that held the stock in place, then you had to push two buttons, one on each side of the saw cabinet away from the blade, that set the blade spinning and automatically brought it down to make the cut. Very safe unless you were trying to hurt yourself.

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